Rocks and Scenery of the Peak District

Trevor D. Ford (Landmark Collector's Library)

The first geology of the Peak District book I am going to read is this excellent little book published in 2006. The name of Trevor Ford will come up again and again in this blog as he has published widely on this subject. This book is aimed at the non specialist and is full of fantastic pictures to inspire an interest in geology. I will go through each chapter with a short synopsis a pattern I will repeat for all the books. In this way we can slowly build up our knowledge in bite sized pieces.

The limestones of the white peak

Limestones form the centre of the peak. They formed in warm tropical waters when Britain was near the equator in the Carboniferous. The area was an atoll like structure surrounded by reefs, although these did not form a continuous ring in time or space. The reefs were not formed of coral but algae and indeed some are better described as mud mounds than reefs. There was a lagoonal plateau in the middle.

Toadstones or volcanic lavas and ash falls

Bubbling under this atoll basalt lava seeped out onto the floor. There is also evidence of ash fall, hexagonal jointing and sills. Wow. Toadstone is a local name for this rock type but the origin is unclear.

The Millstone Grit

Surrounding the limestone to the west, north and east are the shale and sandstone sequences of the dark peak. These were formed by deltas resulting from the erosion of large mountains in the north. About 300 million years ago the lagoon subsided and the mountains raised resulting in the cessation of limestone and the deposition of sandstone which eventually covered the limestone.

Structures, folds and faults

There is a large scale anticline covering the whole of the South Pennines with the Derbyshire massif in the middle.

Minerals and mines

There is a long history of mining in the Peak District and we will return to it again and again. Galena, fluorspar, barite and calcite were all mined in the White Peak from deposits laid down at the end of the Carboniferous. Rakes and scrins are vertical fissure deposits with flats and pipes along the bedding or in caves. There is also Blue John but we will leave that for another day.

Before the ice age: the pocket deposits

Around Brassington are pockets of sand formed by the erosion of Triassic sandstones into a limestone basin 7 million years ago. Originally a sheet the pockets formed as the limestone eroded. They form an unusual landscape as the heathland vegetation of the silica pockets contrasts with the limestone vegetation.

The great ice age

The last ice advance, the Devensian (80-10 kya), did not reach the Peak District stopping only as far south as York and South Staffordshire. The earlier Anglian (470-420 kya) did reach the Peak but the flow was too slow to carve the U-shaped vallys.

The remaining 10 chapters are all short reports about more geomorphological features such as rivers, caves, dry valleys, landslips etc all of which I am sure we will have lots more to say about in the coming months.

This book is now out of print but it features many colour photos and geological sketch maps and is well worth getting hold of.

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